- Arch Linux Wiki (best Linux-related wiki I know)
- Free Software Directory (by FSF.org)
- FossHub (Hosting platform for free software)
- System Administrator’s Guide for Red Hat Enterprise Linux / CentOS 7 (awesome documentation, download the PDF!)
- TUXEDO Computers (Linux-compatible computers)
GitLab instances:
- codecoop.org (hosted by so36.net)